Hi @neuroscirn,
This is a MySQL error message, not an OJS error message; you might find some helpful guidance e.g. on StackOverflow: mysql - Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '=' - Stack Overflow
If you were able to resolve the issue, please post the resolution in case someone else runs into it.
Regards,
Alec Smecher
Public Knowledge Project Team